Cocaine self-administration in monkeys by chewing and smoking

Two rhesus monkeys self-administered cocaine hydrochloride in a gum base vehicle on a fixed ratio 10 schedule with performance characterized by frequent pauses and increased intertrial interval responding. Three other monkeys self-administered cocaine base in lettuce cigarette vehicles in smoking performance marked by shortened puff durations. Urinary benzoyl ecgnoine levels correlated with amount of cocaine chewed or smoked. Monkeys did not prefer cocaine gum in choice tests with plain or procaine gum, but did significantly prefer cocaine cigarettes to plain cigarettes. These preliminary results emphasize the importance of route of administration in determining reinforcement efficacy of human coca use and suggest animal models for their further experimental analysis.